1. Field of Invention
The present invention relates to a projector for projecting and displaying images.
2. Description of Related Art
In a projector, light emitted from an illumination system is modulated by liquid crystal panels or the like according to image information (image signals), and the modulated light is projected onto a screen, thereby achieving image display.
FIG. 11 is an explanatory view showing the principal part of a conventional projector. The projector may consist of three liquid crystal light valves 900R, 900G, and 900B, a cross-dichroic prism 920, and a projection system 940. Colored light of the three colors, red (R), green (G), and blue (B) emitted from an illumination system (not shown) passes through the liquid crystal light valves 900R, 900G, and 900B, and is thereby modulated according to image information. The modulated light (modulated light beams) is synthesized by the cross-dichroic prism 920, and the synthesized light is projected by the projection system 940. A color image is thereby displayed on a screen SC.
The first liquid crystal light valve 900R includes a liquid crystal panel 901R, and two polarizers 902Ri and 902Ro attached to the light incident side and the light emitting side of the liquid crystal panel 901R, respectively. The first polarizer 902Ri on the light incident side transmits light polarized in the same direction as the polarization axis of incident light. Since it is assumed that light incident on the first polarizer 902Ri is polarized in almost the same direction as the polarization axis of the first polarizer 902Ri in FIG. 11, most of the incident light passes unchanged through the first polarizer 902Ri. The light which passed through the first polarizer 902Ri is converted into light polarized in a predetermined direction by the liquid crystal panel 901 R and the second polarizer 902Ro, and is then emitted. This also applies to the second and third liquid crystal light valves 900G and 900B.
When the liquid crystal light valve is irradiated with light emitted from the illumination system, in general, the polarizer in the liquid crystal light valve generates heat. In this case, the temperature of the polarizer sometimes increases to a temperature as high as approximately 80xc2x0 C. This is because light which does not pass through the polarizer is absorbed by the polarizer. Since it is assumed that light polarized in almost the same direction as the polarization axis of the polarizer on the light incident side enters the liquid crystal light valves 900R, 900G, and 900B in FIG. 11, the polarizers 902Ri, 902Gi, and 902Bi on the light incident side generate a relatively small amount of heat. In contrast, since the polarizers 902Ro, 902Go, and 902Bo on the light emitting side transmit only light polarized in a predetermined direction of the light modulated by the liquid crystal panels, and absorb the light polarized in other directions, they generate a relatively large amount of heat. If a black image is displayed on the screen SC, the polarizers 902Ro, 902Go, and 902Bo on the light emitting side absorb most of the incident light, and therefore, they generate an enormous amount of heat.
When the polarizer thus generates heat, since it is attached to the liquid crystal panel, thermal stress is produced therein. Even when the polarizer is attached to a lens or a prism, thermal stress is similarly produced therein. FIG. 12 is a plan view of the second polarizer 902Ro attached to the light emitting side of the first liquid crystal panel 901R, as viewed from the xe2x88x92x-direction. Thermal stress inside the polarizer acts in the directions of the arrows in FIG. 12, and the polarizer becomes distorted due to thermal stress. While this distortion also depends on the intensity distribution of light incident on the polarizer, in general, the distortion is greatest particularly in areas enclosed by broken lines in FIG. 12, that is, at the four corners of the substantially rectangular polarizer 902Ro. When the polarizer is thus distorted, it cannot exhibit desired properties. That is, the polarizer 902Ro transmits the light to be shielded and shields the light to be transmitted. In this case, light emitted from the distorted portions of the polarizer is elliptically polarized, and the intensity of the light is sometimes higher or is sometimes lower than in a normal case in which linearly polarized light is emitted. It is believed that such a phenomenon occurs because the molecular structure of the polarizer undergoes distortion, and that it also depends on the arrangement of liquid crystal molecules which determines the polarizing direction of the light incident on the polarizer 902Ro. When thermal stress thus occurs in the polarizer 902Ro, modulated light beams emitted therefrom are uneven in intensity. Therefore, when a color image is displayed on the screen SC by synthesizing the modulated light beams, it is uneven in color. Similarly, when a monochrome image is displayed on the screen SC, it is uneven in brightness.
The present invention has been made to at least overcome the above problems in the conventional art. One exemplary object of the present invention is to provide a technique for at least reducing unevenness in brightness and color of images to be displayed by a projector.
A device in accordance with an exemplary embodiment of the present invention is a projector which may include:
an illumination system for emitting illumination light;
an electro-optical device for modulating light from the illumination system according to image information; and
a projection system for projecting a modulated light beam obtained by the electro-optical device.
The electro-optical device of this exemplary embodiment preferably has a polarizer on at least one of the light incident side and the light emitting side, and the polarizer is preferably attached to a flexible and transmissive plate material that bends in response to changes in shape of the polarizer.
In the projector of this exemplary embodiment of the present invention, the polarizer is preferably attached to a flexible and transmissive plate material that bends in response to changes in shape of the polarizer. This can reduce unevenness in the intensity of light emitted from the polarizer. As a result, it is possible to reduce unevenness in brightness and color in displayed images.
In this specification, xe2x80x9cflexibilityxe2x80x9d includes not only the bending property of a plate material, but also the property of returning to its initial shape.
In the above device, it is preferable that the plate material be held by a plate material holding section, and that the plate material holding section hold the substantially rectangular plate material so that the plate material can be bent at least at the four corners thereof.
When the plate material is held in this way, the substantially rectangular plate material can be easily bent at the four corners, at which relatively large deformations due to changes in shape of the polarizer are expected.
In the above device, it is preferable that the plate material holding section hold the plate material so that the plate material can move forward and backward in the traveling direction of light passing therethrough.
In this way, the plate material can be held so as to be bent more easily.
In the above device, it is preferable that the plate material holding section hold the plate material by elastically pressing the plate material inward at a side face thereof.
This makes it possible to hold the plate material according to the bending thereof.
Alternatively, in the above device, the plate material may be attached to a transmissive member via a gel adhesive.
Since this allows the gel adhesive to be deformed easily, the plate material can be held so as to be bent in response to changes in shape of the polarizer.
A device in accordance with another exemplary embodiment of the present invention is a projector for projecting and displaying a color image. The device may include:
an illumination system for emitting illumination light;
a colored light separating system for separating the illumination light emitted from the illumination system into first colored light, second colored light and third colored light having three color components;
first electro-optical device, second electro-optical device and third electro-optical device for respectively modulating the first colored light, the second colored light and the third colored light separated by the colored light separating system according to image information, and for thereby respectively generating first modulated light beam, second modulated light beam and third modulated light beam;
a color synthesizing section for synthesizing the first modulated light beam, the second modulated light beam and the third modulated light beam; and
a projection system for projecting synthesized light emitted from the color synthesizing section.
In this exemplary embodiment, each of the first to third electro-optical devices preferably has a polarizer on at least one of the light incident side and the light emitting side, and the polarizer is attached to a flexible and transmissive plate material that bends in response to changes in shape of the polarizer.
In the projector of this exemplary embodiment, the polarizer is also preferably attached to a flexible and transmissive plate material that bends in response to changes in shape of the polarizer. Therefore, since it is possible to reduce unevenness in color of light emitted from the electro-optical devices, it is possible to reduce unevenness in color of an image to be displayed by the synthesized modulated light beak